Parker Giant Eyedropper Fountain pen

Parker Giant Eyedropper fountain pens

The Parker Giant was one of the pen that my Sifu, Mr Lee has advised me to hunt (owing to its size and its reality). When holding in your hand, it feels like the fattest cigar one can find. No one knows why it was build that way. Some says its for salesman demonstration. My question is if its for salesman demonstration use, wouldn't it better to use a transparent demonstrator pen? Perhaps transparent pen were not invented and ready then. Maybe it was build so huge that it can contain more ink and eliminate the need to refill the pen?

Look at the size of the vintage Parker Giant fountain pen vs. the modern day Parker above!